1. Field of the Invention
The present invention relates to a holographic recording medium, a method for manufacturing the same, and an exposure method using the same. More specifically, the invention relates to a holographic recording medium, a method for manufacturing the same, and an exposure method using the same, by which adverse effects of distortion or irregularities of the surface of an exposure object can be reduced. In addition, the present invention relates to a method for a manufacturing a semiconductor device.
2. Description of the Related Art
In recent years, an exposure technique using holography has drawn attention as a pattern formation method in the process of manufacturing a semiconductor device. The exposure technique using holography includes a first step (a recording step) of recording a hologram into a medium for the recording of a hologram by illuminating the holographic recording medium with an object beam and a reference beam, i.e., a step of forming a holographic recording medium, and a second step (a reconstruction step) of illuminating the holographic recording medium with a reconstruction beam, so that a reconstruction image of the fringe pattern that is formed in the holographic recording medium is printed into a resist.
In the recording step, the holographic recording medium is illuminated with a first laser beam (an object beam) through a mask (an original mask) having a desired pattern, and at the same time, the holographic recording medium is illuminated with a second laser beam (a reference beam) from a direction different from the first laser beam. Thus, by illuminating the holographic recording medium with the first laser beam and the second laser beam at the same time, a fringe pattern is recorded in the holographic recording medium. In the reconstruction step, on the other hand, a resist formed over an element formation substrate is illuminated with a laser beam (a reconstruction beam) through the holographic recording medium having the fringe pattern, so that diffraction rays for reproducing the original mask pattern (a reconstruction image) are projected onto the resist.
Research has been conducted on micropattern formation methods (reduction-projection exposure) or the like. For example, in a holographic exposure technique, laser beams that are emitted from different kinds of laser oscillators are used in the recording step and the reconstruction step, so that a pattern with a smaller feature size than the original pattern is printed into a resist (for example, see Reference 1: Japanese Published Patent Application No. 2004-253660).